* {
    margin: 0;
    padding: 0;
}

.container {
    position: fixed;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    min-width: 300px;
    min-width: 100px;
}

.level {
    position: absolute;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    text-align: center;
    margin: 150px auto;
}

.level button {
    padding: 5px 15px;
    background: #00abff;
    border: none;
    color: #fff;
    border-radius: 5px;
    outline: none;
    cursor: pointer;
    font-size: 20px;
    margin: 0 20px;
}

#game {
    position: absolute;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    margin: 200px auto;
}

.end {
    display: none;
    text-align: center;
    margin: -200px auto;
}

.imgs img {

    position: absolute;
    top: 0;
    bottom: 0;
    right: 0;
    left: 0;
    margin: 200px auto;
    display: none;
}

.f-return a img {
    position: absolute;
    left: 0;
    top: 0;
    margin: 10px;
    width: 50px;
    height: 50px;
    cursor: pointer;
}